Mounting structure of semiconductor device and method of manufacturing the same

ABSTRACT

A semiconductor-device mounting structure includes a first semiconductor device and a plate-shaped second semiconductor device connected to the first semiconductor device. The first semiconductor device includes a flexible board, an electronic component, and a sealing resin. The flexible board includes a bendable flexible portion and a hard portion. The flexible portion is bent at a boundary with the hard portion, along a shape of the electronic component such that the flexible board covers the electronic component. The flexible board and the electronic component are sealed with the sealing resin. The first semiconductor device is provided vertical to the second semiconductor device such that the hard portion is provided parallel to the second semiconductor device.

CROSS-REFERENCE OF RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2012-158807, filed on Jul. 17, 2012, theentire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The disclosure relates to a mounting structure of a semiconductor deviceand a method of manufacturing the same.

2. Related Art

In recent years, medical and industrial endoscopes have been widelyused. In an exemplary medical endoscope, an image pickup device such asa CCD is built in a distal end of a body insertion portion. Lesions canbe observed by deeply inserting the insertion portion into the body, andtesting and treatment of the body can be performed by using togetherwith a treatment instrument as needed. In the endoscope, there is a needto achieve a small-sized distal hard portion in which a semiconductordevice is built.

In order to achieve a compact semiconductor device, various methods ofmounting electronic components have been proposed. For example, there isdisclosed a semiconductor device where a flexible board has an electrodeon one surface and an external electrode on the other surface. Theflexible board is bent to cover a plurality of electronic components,and after an inner portion thereof is sealed with a resin, the flexibleboard is mounted so as to be parallel to a motherboard (see, forexample, Japanese Laid-open Patent Publication No. 2001-077294).

SUMMARY

In accordance with some embodiments, a mounting structure of asemiconductor device and a method of manufacturing the same arepresented.

In some embodiments, a semiconductor-device mounting structure includesa first semiconductor device and a plate-shaped second semiconductordevice connected to the first semiconductor device. The firstsemiconductor device includes a flexible board, an electronic component,and a sealing resin. The flexible board includes a bendable flexibleportion and a hard portion. The flexible portion is bent at a boundarywith the hard portion, along a shape of the electronic component suchthat the flexible board covers the electronic component. The flexibleboard and the electronic component are sealed with the sealing resin.The first semiconductor device is mounted vertical to the secondsemiconductor device such that the hard portion is parallel to thesecond semiconductor device.

In some embodiments, a method of manufacturing a semiconductor-devicemounting structure including a first semiconductor device and aplate-shaped second semiconductor device is presented. The firstsemiconductor device includes a flexible board, an electronic component,and a sealing resin. The flexible board includes a bendable flexibleportion and a hard portion. The method includes: connecting theelectronic component to the flexible portion with solder by using areflow method; applying the sealing resin to an entire surface of theflexible board and a lower portion of the electronic component; bendingthe flexible portion along a shape of the electronic component such thatthe flexible board covers the electronic component, and thenpreliminarily fixing the first semiconductor device with a jig; heatingthe preliminarily-fixed first semiconductor device in a furnace to curethe sealing resin; and mounting the cured first semiconductor devicevertical to the second semiconductor device such that the hard portionis parallel to the second semiconductor device, and connecting the firstsemiconductor device to the second semiconductor device.

In some embodiments, a method of manufacturing a semiconductor-devicemounting structure including a first semiconductor device and aplate-shaped second semiconductor device is presented. The firstsemiconductor device includes a flexible board, an electronic component,and a first sealing resin. The flexible board includes a bendableflexible portion and a hard portion. The method includes: connecting theelectronic component to the flexible portion; applying a second sealingresin, which is softer than the first sealing resin that is a UV-curablethermosetting resin, to the hard portion; after applying the secondsealing resin, irradiating the second sealing resin with UV light toenter into a B stage state; applying the first sealing resin to theflexible portion and a lower portion of the electronic component;bending the flexible portion along a shape of the electronic componentsuch that the flexible board covers the electronic component, andpreliminarily fixing the first semiconductor device with a jig; heatingthe preliminarily-fixed first semiconductor device in a furnace to curethe first sealing resin and the second sealing resin; and mounting thecured first semiconductor device vertical to the second semiconductordevice such that the hard portion is parallel to the secondsemiconductor device, and electrically connecting the electroniccomponent to the second semiconductor device.

The above and other features, advantages and technical and industrialsignificance of this invention will be better understood by reading thefollowing detailed description of presently preferred embodiments of theinvention, when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view of a semiconductor-devicemounting structure according to a first embodiment of the presentinvention;

FIGS. 2A to 2D are schematic views for describing a manufacturingprocess of the semiconductor-device mounting structure according to thefirst embodiment of the present invention;

FIG. 3 is a flowchart for describing the manufacturing process of thesemiconductor-device mounting structure according to the firstembodiment of the present invention;

FIG. 4 is a schematic cross-sectional view of a semiconductor-devicemounting structure according to a second embodiment of the presentinvention,

FIG. 5 is a flowchart for describing a manufacturing process of thesemiconductor-device mounting structure according to the secondembodiment of the present invention;

FIGS. 6A to 6D are schematic views for describing the manufacturingprocess of the semiconductor-device mounting structure according to thesecond embodiment of the present invention;

FIG. 7 is a schematic cross-sectional view of a semiconductor-devicemounting structure according to a third embodiment of the presentinvention;

FIG. 8 is a schematic cross-sectional view of a semiconductor-devicemounting structure according to a fourth embodiment of the presentinvention;

FIGS. 9A to 9D are schematic views for describing a manufacturingprocess of the semiconductor-device mounting structure according to thefourth embodiment of the present invention;

FIG. 10 is a schematic cross-sectional view of a semiconductor-devicemounting structure according to a fifth embodiment of the presentinvention;

FIGS. 11A to 11D are schematic views for describing a manufacturingprocess of the semiconductor-device mounting structure according to thefifth embodiment of the present invention;

FIG. 12 is a schematic cross-sectional view of a semiconductor-devicemounting structure according to a sixth embodiment of the presentinvention; and

FIGS. 13A to 13C are schematic views for describing a manufacturingprocess of the semiconductor-device mounting structure according to thesixth embodiment of the present invention.

DETAILED DESCRIPTION

Exemplary embodiments will be described with reference to theaccompanying drawings. The present invention is not limited to theembodiments. In the drawings, the same elements are denoted by the samereference numerals. In addition, it should be noted that the drawingsare schematic, and the relation between thickness and width of eachelement, the ratio of each element, and the like are different from realones. Among figures in the drawings, portions having differentdimensional relations or ratios are included.

FIG. 1 is a schematic cross-sectional view of a semiconductor-devicemounting structure according to the first embodiment of the presentinvention. A semiconductor-device mounting structure 100 according tothe first embodiment includes a first semiconductor device 10 and aplate-shaped second semiconductor device 20.

In the first semiconductor device 10, a flexible board 1 is arranged tocover an electronic component 2, and the flexible board 1 and theelectronic component 2 are adhered to each other with a sealing resin 5.The flexible board 1 includes a flexible portion 3 and a hard portion 4which is formed substantially on the central portion of the flexibleportion 3. The hard portion 4 of the flexible board 1 may be formed byattaching a reinforcement plate to the flexible portion 3.Alternatively, the flexible board 1 may be configured by using acommercially-available rigid flexible board. In addition, in thespecification, the electronic component 2 and the second semiconductordevice 20 denote semiconductor chips, semiconductor package parts, andprinted wire boards. However, the electronic component 2 and the secondsemiconductor device 20 may be a structure part such as a case.

On the flexible portion 3, an electrode 7 is formed on the side wherethe electronic component 2 is mounted. The electrode 7 is configured tobe connected to the electronic component 2. On the hard portion 4, anexternal electrode 6 is formed on the side where the secondsemiconductor device 20 is mounted. The external electrode 6 isconfigured to be connected to the second semiconductor device 20.Preferably, a length T₁ of the hard portion 4 is substantially equal toa thickness T₄ of a bottom surface of the electronic component 2.Assuming that the length T₁ of the hard portion 4 is substantially equalto the thickness T₄ of the bottom surface of the electronic component 2,and the flexible portion 3 is bent at the boundary with the hard portion4, the flexible portion 3 can be bent along a shape of the electroniccomponent 2. In the specification, assuming that the electroniccomponent 2 is a rectangular body, the bottom surface of the electroniccomponent 2 denotes a plane of minimum area.

The electronic component 2 includes an electrode 8 on the side surfaceof thereof to be connected to the flexible board 1. The electrode 8 isconnected to the electrode 7 on the flexible board 1 with a conductivemember 9 such as solder. A gap between the flexible board 1 and theelectronic component 2 is sealed with a sealing resin 5. The sealingresin 5 is formed of a thermosetting resin.

An electrode 12 is formed on the second semiconductor device 20 and isconnected to the first semiconductor device 10, that is, to theelectronic component 2 via a conductive member 11 such as Au stud bumpor solder. A connection portion between the first semiconductor device10 and the second semiconductor device 20 is sealed with a sealing resin13. In connection between the first semiconductor device 10 and thesecond semiconductor device 20, the first semiconductor device 10 isprovided vertical to the second semiconductor device 20 such that thesurface of the hard portion 4 is parallel to the second semiconductordevice 20. The first semiconductor device 10 is vertically mountedthrough the bottom surface thereof having the minimum area, so thatpackaging density can be improved.

If the electronic component 2 is covered with the flexible board 1having only the flexible portion 3 without the hard portion 4, theflexible board 1 is formed in an arc shape at the bottom surface of theelectronic component 2. In this situation, if the first semiconductordevice 10 is mounted vertical to the second semiconductor device 20,stress is concentrated at a connecting portion between the flexibleboard 1 and the conductive member 11, which may lead to detachment ofthe connecting portion under severe environment such as high humidity.In contrast, since the hard portion 4 is employed in the firstembodiment, no stress-concentrated point occurs. Therefore, even undersevere environment, it is possible to secure reliability of connectionof the semiconductor-device mounting structure 100.

Next, a method of manufacturing the semiconductor-device mountingstructure 100 according to the embodiment will be described withreference to FIGS. 2A to 2D and FIG. 3. FIGS. 2A to 2D are schematicviews for describing a manufacturing process of the semiconductor-devicemounting structure 100 according to the first embodiment of the presentinvention. FIG. 3 is a flowchart for describing the manufacturingprocess of the semiconductor-device mounting structure according to thefirst embodiment of the present invention. In FIGS. 2A to 2D, electrodesare not illustrated.

First, as illustrated in FIG. 2A, the electronic component 2 isconnected to the flexible board 1 (Step S1: electronic componentconnection process). The electronic component 2 is connected on theflexible portion 3 with a conductive member 9 such as solder.Preferably, the solder connection is performed by using a reflow method.

After the electronic component connection process, as illustrated inFIG. 2B, the sealing resin 5 is applied to the entire surface of theflexible board 1 as well as to a lower portion of the electroniccomponent 2 (Step S2: application process). The sealing resin 5 isfilled into the lower portion of the electronic component 2 throughcapillary phenomenon.

As illustrated in FIG. 2C, the flexible portion 3 is bent in thedirection indicated by the arrow in the figure. As illustrated in FIG.2D, the electronic component 2 is covered with the flexible portion 3,and the shape of first semiconductor device 10 is preliminarily fixed bya jig or the like (Step S3: bending process).

Subsequently, the preliminarily-fixed first semiconductor device 10 isheated in a furnace to cure the sealing resin 5 (Step S4: curingprocess).

The first semiconductor device 10 which is sealed by curing the sealingresin 5 is provided vertical to the second semiconductor device 20 suchthat the hard portion 4 is parallel to the second semiconductor device20, and the first semiconductor device 10 is connected to the secondsemiconductor device 20, so that the semiconductor-device mountingstructure 100 is manufactured (Step S5: connection process).

According to the semiconductor-device mounting structure 100 of thefirst embodiment, since the hard portion 4 is formed at a connectingportion between the first semiconductor device 10 and the secondsemiconductor device 20, even when the flexible board 1 is bent alongthe shape of the electronic component 2, the flexible board 1 is notformed in an arc shape, and thus it is possible to prevent defectiveconnection. In addition, since the first semiconductor device 10 isvertically connected to the second semiconductor device 20, it ispossible to improve the packaging density.

In the first embodiment, although a thermosetting resin is used as thesealing resin 5, a UV-curable thermosetting resin may be used. If theUV-curable thermosetting resin is employed, after the sealing resin 5 isapplied to the flexible board 1, the resin may be irradiated with UVlight to enter into a half-cured state; and then, the flexible portion 3may be bent along the shape of the electronic component 2 andpreliminarily fixed; and heating and curing may be performed. Due to theuse of the UV-curable thermosetting resin, it is possible to reduce heatdamage to the electronic component 2 and the like.

A semiconductor-device mounting structure 200 according to a secondembodiment is different from the semiconductor-device mounting structure100 of the first embodiment in that a second sealing resin is used toseal a gap between a bottom surface of an electronic component and ahard portion. The semiconductor-device mounting structure 200 accordingto the second embodiment will be described with reference to FIG. 4.FIG. 4 is a cross-sectional view of the semiconductor-device mountingstructure 200 according to the second embodiment of the presentinvention.

As illustrated in FIG. 4, in a first semiconductor device 10A, a secondsealing resin 14 seals a gap between a bottom surface of an electroniccomponent 2, a hard portion 4 and a flexible portion 3 in the vicinityof the hard portion 4. In addition, a sealing resin 5 as a first sealingresin seals a gap between a side surface of the electronic component 2and the flexible portion 3. Preferably, the first sealing resin 5 andthe second sealing resin 14 are adhered to each other.

Preferably, the second sealing resin 14 is softer than the first sealingresin 5. Since the second sealing resin 14 is made of a soft material,when an external force is exerted to the first semiconductor device 10A,stress is absorbed by the second sealing resin 14 as a soft material.Therefore, it is possible to prevent the first sealing resin 5 frombeing peeled off from the first semiconductor device 10A as well as toprevent the first semiconductor device 10A from being detached from thesecond semiconductor device 20. In addition, since the vicinity of thehard portion 4 is also sealed with the second sealing resin 14, it ispossible to prevent the flexible portion 3 from being detached from thehard portion 4.

A material having smaller after-curing hardness than the sealing resinmay be used as the second sealing resin 14. For example, in the casewhere an epoxy resin is used as the sealing resin, a urethane resin, asilicon resin, or the like may be used. In addition, preferably, aUV-curable thermosetting resin is used as the second sealing resin 14.In the specification, a UV-curable thermosetting resin refers to a resinwhich can be cured in a B-stage state, that is, a half-cured statehaving plasticity and adhesiveness through UV light irradiation and canbe completely cured by heating.

Next, a method of manufacturing the semiconductor-device mountingstructure 200 according to the embodiment will be described withreference to FIG. 5 and FIGS. 6A to 6D. FIG. 5 is a flowchart fordescribing a manufacturing process of the semiconductor-device mountingstructure 200 according to the second embodiment of the presentinvention. FIGS. 6A to 6D are schematic views for describing themanufacturing process of the semiconductor-device mounting structureaccording to the second embodiment of the present invention. In FIGS. 6Ato 6D, electrodes are not illustrated.

First, as illustrated in FIG. 6A, the electronic component 2 isconnected to the flexible portion 3 (Step S11: electronic componentconnection process), and the second sealing resin 14 is applied to thehard portion 4 (Step S12: second sealing resin application process).

After the application of the second sealing resin 14, as illustrated inFIG. 6B, the second sealing resin 14 is irradiated with UV light toenter into a half-cured state (Step S13: UV light irradiation process).Since the second sealing resin 14 is in a half-cured state, the secondsealing resin 14 can be prevented from being mixed with the firstsealing resin in the following application process.

After the UV light irradiation process, as illustrated in FIG. 6C, thefirst sealing resin 5 is applied to the flexible portion 3 and to thelower portion of the electronic component 2 (Step S14: applicationprocess). Then, as illustrated in FIG. 6D, the flexible portion 3 isbent along the shape of the electronic component 2 and the shape of thefirst semiconductor device 10A is preliminarily fixed with a jig or thelike (Step S15: bending process). Next, heating treatment is performedin a furnace to cure the first sealing resin 5 and the second sealingresin 14 (Step S16: curing process).

Next, the first semiconductor device 10A is provided vertical to thesecond semiconductor device 20 such that the hard portion 4 is parallelto the second semiconductor device 20, and the first semiconductordevice 10A is connected to the second semiconductor device 20, so thatthe semiconductor-device mounting structure 200 is manufactured (StepS17: connection process).

According to the semiconductor-device mounting structure 200 of thesecond embodiment, since the soft second sealing resin 14 is used toseal the gap between the bottom surface of the electronic component 2and the hard portion 4, when an external force is exerted to the firstsemiconductor device 10A, stress can be absorbed by the second sealingresin 14. Therefore, it is possible to prevent destruction inconnection. In addition, similarly to the first embodiment, since thehard portion 4 is provided on the side where the first semiconductordevice 10A is connected to the second semiconductor device 20, even whenthe flexible board 1 is bent along the shape of the electronic component2, the flexible board 1 is not formed in an arc shape, and thus it ispossible to prevent defective connection. In addition, since the firstsemiconductor device 10A is vertically connected to the secondsemiconductor device 20, it is possible to improve the packagingdensity.

In the second embodiment, by using a soft material as the second sealingresin 14 and using a UV-curable thermosetting resin, the mixing of thesealing resin 5 and the second sealing resin 14 can be prevented. Thefirst sealing resin 5 may be a UV-curable thermosetting resin. In thiscase, the first sealing resin 5 may be applied to the flexible portion3, the resin may be irradiated with UV light to enter into a B-stagestate, and the second sealing resin 14 may be applied to the hardportion 4, so that the same effect can be obtained.

A semiconductor-device mounting structure according to a thirdembodiment is different from the semiconductor-device mounting structure100 according to the first embodiment in that an air gap is formedbetween a bottom surface of an electronic component and a hard portion.The semiconductor-device mounting structure according to the thirdembodiment will be described with reference to FIG. 7. FIG. 7 is across-sectional view illustrating the semiconductor-device mountingstructure according to the third embodiment of the present invention.

As illustrated in FIG. 7, a first semiconductor device 10B includes anair gap 15 between a bottom surface of an electronic component 2 and ahard portion 4. A sealing resin 5 is configured to seal a gap between aside surface of the electronic component 2 and a flexible portion 3.

In a semiconductor-device mounting structure 300 according to the thirdembodiment, due to the air gap 15, when an external force is exerted tothe first semiconductor device 10B, since the flexible portion 3 in thevicinity of the air gap 15 is deformed to absorb stress, it is possibleto prevent the first semiconductor device 10B from being detached from asecond semiconductor device 20. In addition, similarly to the firstembodiment, since the hard portion 4 is provided in the firstsemiconductor device 10B on the side where the second semiconductordevice 20 is connected, even when the flexible board 1 is bent along theshape of the electronic component 2, the flexible board 1 is not formedin an arc shape, and it is possible to prevent defective connection. Inaddition, since the first semiconductor device 10B is verticallyconnected to the second semiconductor device 20, it is possible toimprove packaging density.

In the above described second embodiment, when the temperature of themounting structure is changed after assembling the semiconductor-devicemounting structure, and if the thermal expansion coefficient of thefirst sealing resin is different from that of the second sealing resin,thermal stress is generated in the vicinity of the boundary between thefirst sealing resin and the second sealing resin and thus destructionsuch as peeling of resin may occur. However, in the third embodiment, itis possible to prevent the thermal stress from being generated byproviding the air gap 15 instead of the second sealing resin.

A semiconductor-device mounting structure according to a fourthembodiment is different from the semiconductor-device mounting structure100 according to the first embodiment in that a second electroniccomponent is mounted on a hard portion. The semiconductor-devicemounting structure according to the fourth embodiment will be describedwith reference to FIG. 8. FIG. 8 is a cross-sectional view illustratingthe semiconductor-device mounting structure according to the fourthembodiment of the present invention.

As illustrated in FIG. 8, in a semiconductor-device mounting structure400 according to the fourth embodiment, a second electronic component 16is mounted on a hard portion 4. The second electronic component 16 is achip passive part, a package part, a semiconductor chip, or the like.

Next, a manufacturing process of the semiconductor-device mountingstructure 400 according to the fourth embodiment will be described withreference to the drawings. FIGS. 9A to 9D are schematic views fordescribing a manufacturing process of the semiconductor-device mountingstructure 400 according to the fourth embodiment of the presentinvention. In FIGS. 9A to 9D, electrodes are not illustrated.

First, as illustrated in FIG. 9A, an electronic component 2 is connectedto a flexible portion 3, and the second electronic component 16 isconnected to the hard portion 4.

After the connection, as illustrated in FIG. 9B, a sealing resin 5 isapplied to the entire surface of the flexible board 1. Next, asillustrated in FIG. 9C, the flexible portion 3 is bent, and theelectronic component 2 and the second electronic component 16 arecovered with the flexible board 1, as illustrated in FIG. 9D.

Next, a first semiconductor device 10C is heated to cure the sealingresin 5. The first semiconductor device 10C is vertically mounted sothat the hard portion 4 is parallel to the second semiconductor device20, and the first semiconductor device 10C is connected to the secondsemiconductor device 20, so that the semiconductor-device mountingstructure 400 is manufactured.

In the semiconductor-device mounting structure 400 according to thefourth embodiment, since the second electronic component 16 can bemounted between the electronic component 2 and the hard portion 4, it ispossible to further improve packaging density. In addition, similarly tothe first embodiment, since the hard portion 4 is provided in the firstsemiconductor device 10C on the side where the second semiconductordevice 20 is connected, even when the flexible board 1 is bent along theshape of the electronic component 2, the flexible board 1 is not formedin an arc shape, and it is possible to prevent defective connection.

A semiconductor-device mounting structure according to a fifthembodiment is different from the semiconductor-device mounting structure100 according to the first embodiment in that a position regulatingmember is provided on a second semiconductor device in the vicinity of amounting position of a first semiconductor device to regulate a mountingposition of a first semiconductor device. The semiconductor-devicemounting structure according to the fifth embodiment will be describedwith reference to FIG. 10. FIG. 10 is a cross-sectional view of thesemiconductor-device mounting structure according to the fifthembodiment of the present invention.

As illustrated in FIG. 10, a second semiconductor device 20D accordingto the fifth embodiment includes a dam 17 as a position regulatingmember which regulates a mounting position of the first semiconductordevice 10 in the vicinity of the mounting position of the firstsemiconductor device 10. The first semiconductor device 10 is fit intothe dam 17, so that the mounting position of the first semiconductordevice 10 is regulated. The dam 17 may be formed by using a thick filmmetal or a thick film resin such as photoresist.

Next, a manufacturing process of a semiconductor-device mountingstructure 500 according to the fifth embodiment will be described withreference to the drawings. FIGS. 11A to 11D are schematic views fordescribing a manufacturing process of the semiconductor-device mountingstructure 500 according to the fifth embodiment of the presentinvention. In FIGS. 11A to 11D, electrodes are not illustrated.

As illustrated in FIG. 11A, the dam 17 is formed at the mountingposition of the first semiconductor device 10, and then, as illustratedin FIG. 11B, a conductive member 11 is formed on an electrode. Next, asillustrated in FIG. 11C, a sealing resin 13 is applied to an innerportion of the dam 17 on the second semiconductor device 20D. The firstsemiconductor device 10 which is manufactured through the same processesas Steps S1 to S4 of the first embodiment is mounted vertical to thesecond semiconductor device 20D and connected to the secondsemiconductor device 20D such that the hard portion 4 is parallel to thesecond semiconductor device 20D and the first semiconductor device 10 isfit into the dam 17, so that the semiconductor-device mounting structure500 is manufactured as illustrated in FIG. 11D.

According to the semiconductor-device mounting structure 500 of thefifth embodiment, since the mounting position of the first semiconductordevice 10 can be regulated by the dam 17, the position can easily bealigned, so that the semiconductor-device connection structure can bemanufactured more easily.

In addition, the dam 17 is made of a conductive material such as metaland may serve as a part of a signal line and a ground pattern bybringing the dam into contact with a signal line or a ground pattern ofthe first semiconductor device and a signal line or ground pattern ofthe second semiconductor device, or by the electrical conduction throughthe conductive material. In this way, it is possible to further improvethe degree of the freedom in design of the board and electricalproperties.

In addition, since the hard portion 4 is provided in the firstsemiconductor device 10 on the side where the second semiconductordevice 20D is connected, even when the flexible board 1 is bent alongthe shape of the electronic component 2, the flexible board 1 is notformed in an arc shape, and it is possible to prevent defectiveconnection. In addition, since the first semiconductor device 10 isvertically connected to the second semiconductor device 20D, it ispossible to improve packaging density.

A semiconductor-device mounting structure according to a sixthembodiment is different from the semiconductor-device mounting structureaccording to the first embodiment in that alignment marks are formed ina first semiconductor device and a second semiconductor device, andafter the first semiconductor device is connected to the secondsemiconductor device, a flexible portion is bent, so that thesemiconductor-device mounting structure is manufactured. Thesemiconductor-device mounting structure according to the sixthembodiment will be described with reference to FIG. 12. FIG. 12 is across-sectional view of the semiconductor-device mounting structureaccording to the sixth embodiment of the present invention.

As illustrated in FIG. 12, in a first semiconductor device 10E accordingto the sixth embodiment, a flexible portion 3E is formed so as to beshort, and a flexible board 1E is formed in an “L” shape so as to coveronly one side surface and bottom surface of an electronic component 2.

On an outer surface of the flexible board 1E, an alignment mark 18 isformed opposite the electronic component 2. The alignment mark 18 isused for position alignment together with an alignment mark 19 which isformed on a second semiconductor device 20E on the side where the firstsemiconductor device 10E is mounted. The alignment marks 18 and 19 maybe formed simultaneously during the formation of a pattern such as anelectrode.

Next, a manufacturing process of the semiconductor-device mountingstructure 600 according to the sixth embodiment will be described withreference to the drawings. FIGS. 13A to 13C are schematic viewsillustrating the manufacturing process of the semiconductor-devicemounting structure 600 according to the sixth embodiment of the presentinvention.

As illustrated in FIG. 13A, the alignment marks 18 and 19 are observedwith a camera of a mounting apparatus, the first semiconductor device10E and the second semiconductor device 20E are aligned with each otherbased on the positions of the alignment marks 18 and 19 and areconnected to each other. In the first semiconductor device 10E, theelectronic component 2 is connected to the flexible portion 3E, and asealing resin 5 is applied to the entire surface of the flexible board1E. Next, the first semiconductor device 10E is connected to the secondsemiconductor device 20E while the flexible portion 3E is not bent.

After the connection of the first semiconductor device 10E and thesecond semiconductor device 20E, as illustrated in FIG. 13B, a sealingresin 13 is applied to the connection portion. Next, as illustrated inFIG. 13C, the flexible portion 3E is bent along the shape of theelectronic component 2, and heating treatment is performed to cure thesealing resins 5 and 13 and to seal while the flexible portion 3E isbent, so that the semiconductor-device mounting structure 600 can bemanufactured. The sealing resin 13 may be applied before the firstsemiconductor device 10E is connected to the second semiconductor device20E.

According to the semiconductor-device mounting structure 600 of to thesixth embodiment, it is possible to perform position alignment of thefirst semiconductor device 10E and the second semiconductor device 20Eby using the alignment marks 18 and 19. In addition, since the firstsemiconductor device 10E is vertically connected to the secondsemiconductor device 20E, it is possible to improve packaging density.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A semiconductor-device mounting structurecomprising: a first semiconductor device including a flexible board, anelectronic component, and a sealing resin; and a plate-shaped secondsemiconductor device connected to the first semiconductor device,wherein the flexible board includes a bendable flexible portion and ahard portion, the flexible portion is bent at a boundary with the hardportion, along a shape of the electronic component such that theflexible board covers the electronic component, the flexible board andthe electronic component are sealed with the sealing resin, and thefirst semiconductor device is mounted vertical to the secondsemiconductor device such that the hard portion is parallel to thesecond semiconductor device; wherein the first semiconductor devicefurther includes a second sealing resin which is softer than the sealingresin as a first sealing resin and seals a gap between a bottom surfaceof the electronic component, the hard portion and the flexible portionin a vicinity of the hard portion, and the first sealing resin seals agap between a side surface of the electronic component and the flexibleportion.
 2. The semiconductor-device mounting structure according toclaim 1, wherein one or both of the first sealing resin and the secondsealing resin is formed of a UV-curable thermosetting resin.
 3. A methodof manufacturing a semiconductor-device mounting structure including afirst semiconductor device and a plate-shaped second semiconductordevice, the first semiconductor device including a flexible board, anelectronic component, and a sealing resin, the flexible board includinga bendable flexible portion and a hard portion, the method comprising:connecting the electronic component to the flexible portion with solderby using a reflow method; applying the sealing resin to an entiresurface of the flexible board and a lower portion of the electroniccomponent; bending the flexible portion along a shape of the electroniccomponent such that the flexible board covers the electronic component,and then preliminarily fixing the first semiconductor device with a jig;heating the preliminarily-fixed first semiconductor device in a furnaceto cure the sealing resin; and mounting the cured first semiconductordevice vertical to the second semiconductor device such that the hardportion is parallel to the second semiconductor device, and connectingthe first semiconductor device to the second semiconductor device. 4.The method according to claim 3, wherein the sealing resin is aUV-curable thermosetting resin, and after applying the sealing resin,the UV-curable thermosetting resin is irradiated with UV light to enterinto a B-stage state.
 5. A method of manufacturing asemiconductor-device mounting structure including a first semiconductordevice and a plate-shaped second semiconductor device, the firstsemiconductor device including a flexible board, an electroniccomponent, and a first sealing resin, the flexible board including abendable flexible portion and a hard portion, the method comprising:connecting the electronic component to the flexible portion; applying asecond sealing resin, which is softer than the first sealing resin thatis a UV-curable thermosetting resin, to the hard portion; after applyingthe second sealing resin, irradiating the second sealing resin with UVlight to enter into a B stage state; applying the first sealing resin tothe flexible portion and a lower portion of the electronic component;bending the flexible portion along a shape of the electronic componentsuch that the flexible board covers the electronic component, andpreliminarily fixing the first semiconductor device with a jig; heatingthe preliminarily-fixed first semiconductor device in a furnace to curethe first sealing resin and the second sealing resin; and mounting thecured first semiconductor device vertical to the second semiconductordevice such that the hard portion is parallel to the secondsemiconductor device, and electrically connecting the electroniccomponent to the second semiconductor device.